Finding the Fourth Proportional to 1,380.60, 1,904.82 and 820.62

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.60 : 1,904.82 = 820.62 : x
2. Step 2: Convert to fraction form
   1,380.60/1,904.82 = 820.62/x
3. Step 3: Cross multiply
   1,380.60x = 1,904.82 × 820.62
4. Step 4: Simplify right side
   1,380.60x = 1,563,133.39
5. Step 5: Solve for x
   x = 1,563,133.39/1,380.60
6. Step 6: Final answer
   x = 1,132.21